This medical valve (1) comprises a body (2) provided with three female connectors (5a, 5b, 5c) and a male connector (6), at least one (5c) of the female connectors (5a, 5b, 5c) being designed to receive an injection syringe, and a mobile plug (3), which is mounted in the body (2), is provided with a rotation lever and comprises a fluid circulation channel. The female connector (5c) designed to receive an injection syringe comprises an indexing means in order to prevent a mixing syringe from being mounted on this connector (5c). The invention also relates to a kit for preparing a product to be injected, said kit comprising such a medical valve (1). The invention also relates to a method for preparing a mixture or an emulsion which is intended to be injected into a patient with the aid of such a medical valve (1).
